Hydrophobic film coated with acid-modified butadiene copolymer

ABSTRACT

A hydrophobic film is coated with an ethylenically unsaturated acid-modified butadiene copolymer and a light sensitive gelatinsilver halide emulsion layer.

United States Patent 1 Clachan et al.

[ ]*Nov. 27, 1973 HYDROPI-IOBIC FILM COATED WITH ACID-MODIFIED BUTADIENECOPOLYMER Inventors: Margaret Loudon Clachan,

Manningtree; Gordon Edmund Alfred Pears, Welwyn Garden City, both ofEngland Appl. No.: 142,407

Related US. Application Data Division of Ser. No. 829,807, June 2, 1969,Pat. No. 3,615,556.

Foreign Application Priority Data June 24, 1968 Great Britain 30,029/68[52] US. Cl. 117/76 F, 96/87 R, l17/138.8 F,

117/161 UD [51] Int. Cl G03c 1/80 [58] Field of Search 96/87 R; 117/161UD,

ll7/76 F, 138.8 F

{5 6] References Cited UNITED STATES PATENTS 3,615,556 10/1971 Clachenet al. 96/87 R 3,506,445 4/1970 Abbott et al 96/87 R PrimaryExaminer-Ronald H. Smith Attorney-Cushman, Darby & Cushman [5 7 ABSTRACTA hydrophobic film is coated with an ethylenically unsaturatedacid-modified butadiene copolymer and a light sensitive gelatin-silverhalide emulsion layer.

8 Claims, No Drawings HYDROPHOBIC FILM COATED WITH ACID-MODIFIEDBUTADIENE COPOLYMER This application is a divisional application of Ser.No. 829,807, filed June 2, 1969, now US. Pat. No. 3,615,556.

This invention relates to film base materials suitable for use, interalia, as base materials for photographic films carrying a coating of agelatino silver halide photographic emulsion.

A wide variety of self-supporting film materials have been proposed foruse as supports in the production of photographic film. Generally suchfilm materials are essentially hydrophobic in character and materialssuch as polyethylene terephthalate, which because of its chemical andphysical properties is increasingly in use for the purpose, are highlyhydrophobic.

In the production of photographic materials using such film supports,where the light sensitive layer is a gelatino silver halide layer thereis considerable difficulty in securing adequate anchorage between theessentially hydrophilic emulsion layer and the hydrophobic support film,especially bearing in mind that the anchorage must remain unaffected bythe quite vigorous chemical treatments to which the photographic filmwill be subjectedin the processing of the photographic image.

It is known that the anchorage may be improved by the introduction,between the film support and the hydrophilic layer applied thereto, ofone or more interlayers of suitable film-forming polymeric materials.Many such proposals have been made in the past and have met with varyingdegrees of success. It is an object of the present invention to providea film base which comprises a hydrophobic film support having a layercoated thereon and which is adapted to receive a hydrophilic coating andthereby 'to establish an assembly of which the layers are very stronglyanchored together.

According to the present invention there is provided a coated film basematerial which comprises a support film of synthetic film-formingmaterial of hydrophobic character and superimposed thereon a layer of acomposition comprising a copolymer of (l) butadine, (2) an ethylenicallyunsaturated carboxylic acid, and (3) at least one other ethylenicallyunsaturated monomer copolymerisable therewith, the said copolymercontaining from 18 to 70 percent by weight of butadiene units and from0.5 to 20 percent by weight of units of the ethylenically unsaturatedcarboxylic acid.

The support film may be of any plastics material, especially suchmaterials as are highly hydrophobic, examples being films consistingessentially of polyolefines such as polyethylene, polypropylene,poly-4-methyl pentene-l, and copolymers of such olefines with each otheror with other ethylenically unsaturated monomers, polyesters such aspolyethylene terephthalate and synthetic linear polycarbonates, andcellulose derivatives such as cellulose diacetate or triacetate oracetobutyrate. The support film may be molecularly oriented in one ortwo directions in its plane before and/or after the application of theanchoring layer thereon. It may also be heat set. The invention is ofparticular value where the film material is biaxially oriented and heatset polyethylene terephthalate both because that material has physicaland chemical properties rendering it particularly suitable for theproduction of photographic materials and because, being highlyhydrophobic, the advantages achieved by the present invention areachieved to excellent effect.

If desired, before the application of the copolymer anchoring coat thesurface of the film may be subjected to a treatment designed to renderit somewhat more capable of readily accepting the copolymer coating. Thenature of such pre-treatment will vary, of course, with the filmmaterial in use but in the case of materials such as the polyolefinesthe film may be usefully subjected to a high voltage stress accompaniesby corona discharge (commonly referred to as C-treatment) or sub jectedto treatment with strong oxidising agents such as fuming sulphuric acid,nitric acid, potassium dichromate or the like. Where the film materialis polyethylene terephthalate a useful effect is obtained bypretreatment with trichloracetic acid or a halogenated phenol. In amodification of this aspect of the invention treatment with the organicmaterials just mentioned may be effected simultaneously with theapplication of the copolymer layer by including such organic materialsin the composition of such layer.

Generally speaking, the base. film material is oriented. As statedabove, the copolymer anchor coat may be applied before the orientationis completed and in this case, pretreatment of the base film surface isnot normally necessary. This method also has the advantage that verythin coatings may be applied uniformly to the base film. Thus coatweights of from 0.8 mg/dm to 4.0 mg/dm of the biaxially oriented filmmay be applied in this way. As indicated above the copolymer used in thepresent invention is a copolymer of three monomeric materials. Of theseone is butadiene, which must be present in a proportion of 18 to percentby weight of the final copolymer. The second monomer is an ethylenicallyunsaturated acid and examples are acrylic acid, methacrylic acid,fumaric acid, itaconic acid, maleic acid and crotonic acid. It is to beunderstood that in the production of the copolymer the anhydrides ofsuch acids may be used instead of the acids themselves. The thirdcomponent is another ethylenically unsaturated monomer and may be, forexample, styrene, a-methyl styrene, methyl methacrylate oracrylonitrile.

' The proportion of butadiene in the copolymer may vary (within thelimits of 18 to 70 percent by weight re ferred to above) in dependenceon the nature of the other monomers present, and in dependance on theproperties required in the coated film which in turn may depend onwhether it is to be immediately coated with a further coating e.g.,based on gelatin or whether it will first be reeled. Thus, for example,if the proportions of butadiene is too great, particularly when thethird component of the copolymer is styrene or methyl methacrylate, thecomposition may become too soft and give rise (when coated on to filmmaterial) to a final film base which shows the phenomenon of blocking,e.g., when wound on a reel. This effect is particularly marked atconcentrations of butadiene greater than 60 percent and even atconcentrations above 30 percent is a noticeable feature of the coatedfilm. To produce the best non-blocking coated film base according to ourinvention therefore we prefer to use concentrations of butadiene in therange l830 percent. In some cases, however, e.g., when the subsequentgelatin coating or coatings are immediately applied without anyintermediate reeling stage or when it is admissable to includeanti-blocking agents in our composition, concentrations of from 30percent to 60 percent preferably from 32 percent to 40 percent by weightof butadiene may be used and are indeed preferred because of the betterfilm-forming properties of the resultant composition. When the thirdcomponent is acrylonitrile, higher proportions of butadiene (e.g., 50 to70 percent) generally afford the best results.

In terms of the second component, the unsaturated acid, it is found thatitaconic acid is particularly useful since this acid leads to excellentadhesion at relatively low concentrations. Thus a preferred copolymercontains, in addition to the butadiene and the third component, from 1to 7 percent itaconic acid, optionally with up to of anotherethylenically unsaturated carboxylic acid.

The copolymer may be applied to the film material by any conventionalcoating technique and is preferably applied in the form of an aqueouslatex, the aqueous medium being dried off, e.g., in an oven at atemperature above 100C. The aqueous latex may contain additives forspecial purposes, e.g.

i. Wetting agents and emulsifiers for imparting stability andwettability, e.g., sodium lauryl sulphate, nonyl phenol ethyleneoxidecondensate, and cetyl trimethyl ammonium bromide.

ii. Colloid stabilisers, e.g., gelatin, polyvinyl pyrolidone andpolyvinyl alcohol.

iii. Adhesion promoters, e.g., chlorophenols, resorcinol andtrichloracetic acid.

iv. Cross-linking agents, e.g., hexamethoxy methyl melamine.

The coated film base as defined will accept with good anchorage a morehydrophilic layer such as a thin layer comprising gelatin which has beenapplied from an organic solvent or aqueous dispersion. The organicsolvent or aqueous dispersion of gelatin may also contain at least onesynthetic polymer or resin, adhesion promoters and cross-linking agents.There may be superimposed on this gelatin containing layer, a lightsensitive gelatino-silver halide emulsion to give a photographic filmproduct showing excellent adhesion of the .assembly of layers throughoutall photographic pro- EXAMPLE 1 Biaxially oriented polyethyleneterephthalate was coated with a solution of 3-methyl-4-chlorophenol inmethanol and dried for 2 minutes at 80C.

A range of butadiene copolymers with composition as given in table belowwere then applied as aqueous latices and dried for 1 minute at 110C togive coat weights approximately 2-3 mgldm TABLE Composition ofCopolymers Wt Buta- Acrylolta Methdiene Styrene nitrile conic acrylicAcrylic Acid Acid Acid An aequeous solution of gelatin containing 3percent formaldehyde on weight of gelatin was coated onto the layer ofbutadiene copolymer and dried to give a coat weight of approximately 2mgldm EXAMPLE 2 An aqueous latex containing a copolymer of butadiene,styrene and itaconic acid 38:58:4 parts by weight, was applied topolyethylene terephthalate film which had been stretched longitudinally.After drying, the coated film was stretched sideways by a factor of 3 atC and heat set at a temperature of 210C for 1 minute.

A gelatin layer was then applied as in Example 1. The film blocked ifreeled prior to the application of the gelatin layer.

EXAMPLE 3 An aqueous latex containing a copolymer of butadiene, styreneand itaconic acid 20:7515 parts by weight, was applied to polyethyleneterephthalate film which had been stretched longitudinally. After dryingthe coated film was stretched sideways by a factor of 3 at C and heatset at a temperature of 210C for 1 minute. The weight of the coating onthe biaxially drawn and heat set film was 1.5 mgldm The resultant filmwas capable of being reeled without any blocking occurring at roomtemperature, and was so reeled. A gelatin layer of the type described inExample 1 was then applied to the film.

A photographic gelatino silver halide emulsion coating was applieddirectly on the top coating of the film products of Examples 1, 2 and 3.The layers were strongly adherent to one another and to the film supportso that the final photographic film could be processed without danger ofseparation of the layers or frilling.

We claim:

1. A coated film base material which includes a support film ofsynthetic film-forming material of hydrophobic character havingsuperimposed thereon at least two layers comprising a first layeradjacent said support film and a second layer consisting essentially ofgelatin applied over the first layer, said first layer having acomposition comprising a copolymer of 1 )butadiene, (2) an ethylenicallyunsaturated carboxylic acid, and (3) at least one other ethylenicallyunsaturated monomer copolymerisable therewith, said copolymer containingfrom 18 to 70 percent by weight of butadiene units and from 0.5 to 20percent by weight of units of the ethylenically unsaturated carboxylicacid.

2. A coated film base material according to claim 1, in which thesupport film is of biaxially oriented and heat set polyethyleneterephthalate.

3. A coated film base material according to claim 1, in which saidcopolymer contains, as the ethylenically unsaturated acid, itaconicacid.

4. A coated film base material according to claim 3, in which the saidcopolymer contains from 1.0 to 7.0 percent by weight of itaconic acid.

5. A coated film base material according to claim 1, I

in which said copolymer contains from 30 to 60 percent by weight ofbutadiene units.

cent by weight of butadiene units.

8. A coated film base material according to claim 1, in which the coatweight of the first layer is from 0.8 mg/dm to 4.0 mg/dm

2. A coated film base material according to claim 1, in which thesupport film is of biaxially oriented and heat set polyethyleneterephthalate.
 3. A coated film base material according to claim 1, inwhich said copolymer contains, as the ethylenically unsaturated acid,itaconic acid.
 4. A coated film base material according to claim 3, inwhich the said copolymer contains from 1.0 to 7.0 percent by weight ofitaconic acid.
 5. A coated film base material according to claim 1, inwhich said copolymer contains from 30 to 60 percent by weight ofbutadiene units.
 6. A coated film base material according to claim 5, inwhich said copolymer contains from 32 to 40 percent by weight ofbutadiene units.
 7. A coated film base material according to claim 1, inwhich said copolymer contains from 18 to 30 percent by weight ofbutadiene units.
 8. A coated film base material according to claim 1, inwhich the coat weight of the first layer is from 0.8 mg/dm2 to 4.0mg/dm2.